1. Field of the Invention
The present invention relates to a substrate cleaning method for performing scrub cleaning of a surface of a substrate, such as a semiconductor wafer, with a long cylindrical roll cleaning member by rotating the substrate and the roll cleaning member each in one direction while keeping the roll cleaning member in contact with the surface of the substrate in the presence of a cleaning liquid, and relates to a roll cleaning member for use in the substrate cleaning method.
The substrate cleaning method of the present invention can be applied to cleaning of a surface of a semiconductor wafer, or to cleaning of a surface of a substrate in the manufacturing of an LCD (liquid crystal display) device, a PDP (plasma display panel) device, a CMOS image sensor, etc.
2. Description of the Related Art
As semiconductor devices are becoming finer these days, cleaning of various films, made of materials having different physical properties and formed in a substrate, is widely practiced. For example, in a damascene interconnect forming process for forming interconnects in a substrate surface by filling a metal into interconnect trenches formed in an insulating film on the substrate surface, an extra metal on the substrate surface is polished away by chemical mechanical polishing (CMP) after the formation of damascene interconnects. A plurality of films such as a metal film, a bather film and an insulating film, having different water wetting properties, are exposed on the substrate surface after CMP.
A residue of a slurry (slurry residue) that has been used in CMP, metal polishing debris, etc. exist on the substrate surface having exposed films such as a metal film, a bather film and an insulating film by CMP. If cleaning of the substrate surface is insufficient and residues remain on the substrate surface, the residues on the substrate surface may cause reliability problems such as the occurrence of leak from a residue portion, poor adhesion, etc. It is therefore necessary to clean with a high degree of cleaning the substrate surface on which the plurality of films such as a metal film, a barrier film and an insulating film, having different water wetting properties, are exposed.
As a cleaning method for cleaning a substrate surface after CMP, a scrub cleaning method is known which comprises cleaning a surface of a substrate, such as a semiconductor wafer, with a long cylindrical roll cleaning member (roll sponge or roll brush) by rotating the substrate and the roll cleaning member each in one direction while keeping the roll cleaning member in contact with the surface of the substrate in the presence of a cleaning liquid (see patent literature 1). A roll cleaning member for use in such scrub cleaning generally has a length which is somewhat larger than the diameter of a substrate, and is disposed in such a position that its central axis (rotational axis) is perpendicular to the rotational axis of the substrate. Cleaning characteristics can be obtained by rubbing the surface of the substrate with the roll cleaning member, i.e., by rotating the substrate on the rotational axis while keeping the roll cleaning member in contact with the surface of the substrate over the entire length in the diametrical direction.
A substrate cleaning method has been proposed which cleans a substrate with a sponge brush (cleaning member) of a rotary brush while ejecting a liquid or a gas from a surface of the rotating rotary brush (see patent literature 2). This method can avoid uneven cleaning and prevent clogging of the brush. As an exemplary sponge brush for use in the substrate cleaning method, the patent literature 2 describes a sponge brush having a spiral groove in the peripheral surface so that a flow of a liquid chemical (cleaning liquid), flowing from the center toward the periphery of a substrate, will be created by the rotation of the rotary brush.
The applicant has proposed a substrate processing apparatus which cleans a substrate by causing the substrate and a roll (roll cleaning member) to rub against each other in an area of the substrate, corresponding to approximately half of the diameter of the substrate (see patent literature 3). In this substrate processing apparatus, the roll and a substrate preferably move in opposite directions in the rubbing area between them. The applicant has also proposed a substrate processing apparatus which cleans a peripheral area of a substrate by causing the substrate and a roll (roll cleaning member) to rub against each other solely in the peripheral area of the substrate (see patent literature 4).
A cleaning sponge roller has been proposed which comprises a roll body (roll cleaning member) whose peripheral portion is divided into a central area which is to make contact with an inner area of a surface to be cleaned, and outer end areas which are to make contact with an outer area of the surface to be cleaned (see patent literature 5). The sponge roller is designed such that the strength of contact of the peripheral portion of the roll body with the surface to be cleaned is lower in the central area than in the outer end areas.